These four lectures by Dr. Tim Keller (from the John Reed Miller Lecture Series) given at Reformed Theological Seminary, Jackson Mississippi, on Nov. 11-13, 2014, are an outstanding resource and help for all preachers. I recommend them highly. - JS
Lecture 1: What is Good Preaching?
Lecture 2: Preaching to Secular People and Secularized Believers
Lecture 3: Preaching the Gospel Every Time
Lecture 4: Preaching to the Heart